Bo ba bat kha thi

MC LC ***** CHNG 1: L THUYT B BA BT KH THI V CC HM CHO VIT NAM 1.1. M HNH MUNDELL-FLEMING V CC HM V CHNH SCH TI KHO, TIN T DI CC CH T GI ---------------------------------------------------------- 12

1.1.1. 1.1.2. 1.2.1. 1.2.2.

Chnh sch ti kho v tin t di ch t gi c nh ---------------------- 12 Chnh sch ti kho v tin t di ch t gi linh hot -------------------- 14 Thuyt b ba bt kh thi ca GS. Robert Mundell ------------------------------- 15 Thuyt tam gic m rng ca Yigang v Tangxian------------------------------ 16

1.2. L THUYT B BA BT KH THI -------------------------------------------------------- 15

1.3. THUYT T DIN (A tetrahedron Hypothesis) ------------------------------------------- 17

1.3.1. C ch t gi trung gian- nn tng ca thuyt tam gic m rng v thuyt t din ------------------------------------------------------------------------------------------ 17 1.3.2. 1.4.1. 1.4.2. 1.4.3. 1.4.4. Thuyt t din ------------------------------------------------------------------------- 18 Chnh sch tin t cha hp l------ ----------------------------------------------- 21 Linh hot trong c ch t gi ------------------------------------------------------- 22 Thc hin chnh sch v hiu ho ------------------------------------------------- 22 Khuyn ngh 1: Tng cng kh nng vay n quc gia bng ni t ---------- 22 CHNG 2 : BI HC T NGI LNG GING PHA BC - TRUNG QUC I LC2.1. TRUNG QUC TIN HNH KIM SOT TI KHON VN (T CUC CI CCH 1979 N NM 1996) ------------------------------------------------------------------------------- 24 2.2. QA TRNH HI NHP KINH T V XU HNG T DO HO TI KHON VN CA TRUNG QUC (GIAI ON 1996 N NAY) ------------------------------------------- 25 1.4. CC HM I VI VIT NAM ---------------------------------------------------------- 21

2.2.1. 2.2.2. 2.2.3. 2.2.4.

p lc m ca nn kinh t to nn xu hng t do ho ti khon vn ------- 25 QFII nh l mt bc i ln hng n t do ho ti khon vn ------------- 26 S pht trin ca th trng c phiu B ------------------------------------------- 27 S bng n ca TTCK v dng vn FPI (t nm 2005 n nay) ------------- 27

2.3. TRUNG QUC DUY TR T GI HI OI C NH -------------------------------- 28 2.4. TC NG CA L THUYT B BA BT KH THI TI TRUNG QUC -------- 29 2.5. BI HC KINH NGHIM CA TRUNG QUC ----------------------------------------- 33

2.5.1. 2.5.2. 2.5.3. 2.5.4.

-1Khuyn ngh 2 : Chnh sch can thip v hiu ho ngy cng khng hiu qu ------------------------------------------------------------------------------------------ 34 Tng gi ng NDT ------------------------------------------------------------------ 35 Khuyn ngh 3: a vn vo sn xut, hn ch u t ti chnh -------------- 35 M ca ti khon vn c l trnh -------------------------------------------------- 36 CHNG 3 : CC VN THC TIN VIT NAM

3.1. THU HT DNG VN NGOI V CHNH SCH KIM SOT VN VN ------- 37 3.2. CHNH SCH T GI CA VIT NAM --------------------------------------------------- 41 3.3. TC NG CA L THUYT B BA BT KH THI VIT NAM ---------------- 42

3.3.1. 3.3.2. 3.3.3. 3.3.4. 3.4.1. 3.4.2. 3.4.3. 3.4.4.

Cung tin v tn dng gia tng----------------------------------------------------- 42 S gia tng ca lm pht ------------------------------------------------------------ 43 Cng thng vn li sut ------------------------------------------------------ 44 Th trng chng khon tt dc ------------------------------------------------ 44 Pht trin TTCK: Li ch cho nh u t hay cho sn xut x hi?------- 45 Quan im CPH v cch thc tin hnh IPO: Ci cch hay tn thu? ---- 45 Ch th 03: Bp bn ny, li bn kia-------------------------------------------- 47 Vn c lp ca UBCK ---------------------------------------------------------- 47 CHNG 4 : NH LNG CC MI QUAN H KINH T V M VIT NAM

3.4. NHNG VN TRONG IU HNH TH TRNG CHNG KHON --------- 44

4.1. KIM NH TC NG CA T GI THC N XUT KHU ------------------- 48 4.2. KIM NH TC NG T GI THC N SN LNG CNG NGHIP ---- 49 4.3. KIM NH TC NG CA CC NHN T N LM PHT-------------------- 49 4.4. KIM NH VAI TR CA DNG VN NGOI I VI TTCK VIT NAM ---- 52 4.5. KIM NH MI QUAN H GIA LM PHT V T SUT SINH LI CHNG KHON VIT NAM ------------------------------------------------------------------------------- 53

CHNG 5 : CON NG NO CHO CHNH SCH KINH T VIT NAM5.1. I VI MC TIU CHNG LM PHT ------------------------------------------------ 57

5.1.1. 5.1.2. 5.1.3. 5.1.4. 5.2.1. 5.2.2. 5.2.3.

-2Khuyn ngh 4: Chuyn t mc tiu t gi sang mc tiu lm pht ----------- 57 Khuyn ngh 5: Thc hin chnh sch tin t tht cht ------------------------- 59 Khuyn ngh 6: Chnh sch ti kho: Tht cht chnh sch ti chnh cng -- 60 Khuyn ngh 7: m bo ngun cung lng thc (gi go) ------------------- 61 Khuyn ngh 8 : Thay i quan im CPH --------------------------------------- 62 Khuyn ngh 9: Nng cao kh nng c lp iu hnh ca UBCK nh nc ------------------------------------------------------------------------------------------- 62 Khuyn ngh 10 : Kim sot cht ch hn dng vn ngoi--------------------- 62

5.2. I VI TH TRNG CHNG KHON ------------------------------------------------ 61

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DANH MC CC T VIT TTTTCK VN FPI FDI GDP NHTW TQ QFII WTO IMF SAFE CSRC PboC NHNN UIP NTNN NHTM (CP) HSBC IPO CHP VCB DNNN Th trng chng khon Vit Nam Dng vn u t gin tip nc ngoi Dng vn u t trc tip nc ngoi Tng sn phm Quc Ni Ngn hng trung ng Trung Quc Nh u t t chc ngoi tiu chun T chc thng mi th gii Qu tin t th gii U ban qun l nh nc v ngoi hi (Trung Quc) U ban lut chng khon Trung Quc Ngn Hng Trung ng Trung Quc Ngn hng nh nc Ngang gi li sut khng c phng nga Nh u t nc ngoi Ngn hng thng mi (c phn) Ngn hng Hng Kng-Thng Hi. Pht hnh c phiu ln u ra cng chng. C phn ho Ngn hng Vietcombank Doanh nghip nh nc.

-4VNM UBCKNN BTC EPS P/E CTE ER RER INDUS CPI EXP IMP LR VAR TSSL DNETBUY Cng ty c phn sa Vit Nam-Vinamilk U ban chng khon nh nc (Vit Nam) B Ti chnh. Thu nhp trn mi c phn Ch s gi/ thu nhp Tn dng cho nn kinh t T gi danh ngha gia VND/USD T gi thc gia VND/USD Sn lng cng nghip Ch s gi tiu dng. Xut khu Nhp khu Li sut cho vay M hnh vc t t hi quy T sut sinh li Chnh lch mua rng ca nh u t nc ngoi

LCPI, LER, K t L pha trc ngha l ly log cho cc bin s CPI, LRER,LINDUS.. ER, RER, INDUS DLCPI,DLINDUS.. K t D pha trc ngha l ly chnh lch ca cc bin s LCPI, LINDUS.. V d. DCPI= CPIt-CPIt-1. ADB CIEM Ngn hng pht trin Chu . Vin nghin cu qun l kinh t trung ng

-5FED HOSE Cc d tr lin bang M S giao dch chng khon TP.HCM

-6-

DANH MC BNGBng 1.1: Nguyn l ca b ba bt kh thi. Bng 1.2: S la chn c ch t gi theo m hnh tam gic bt kh thi. Bng 1.3: S la chn c ch t gi theo thuyt t din. Bng 2.1: D tr ngoi hi Trung Quc 1994-2007. Bng 2.2: ng gp ca d tr ngoi hi n cung tin, 2003-2006. Bng 2.3: Lm pht ca Trung Quc t 2003-2006. Bng 3.1: So snh mc m ca dng vn gin tip. Bng 3.2: So snh mc m ca thng mi. Bng 3.3: Gia tng lm pht, cung tin, tng trng GDP Vit Nam.

-7-

DANH MC HNHHnh 1.1: M hnh IS-LM ca Mundell-Fleming vi t gi c nh. Hnh 1.2: M hnh IS-LM ca Mundell-Fleming vi t gi th ni. Hnh 1.3: Tam gic b ba bt kh thi.Hnh 1.4: Thuyt tam gic m rng ca Yigang v Tangxian.

Hnh 1.5: Thuyt t din. Hnh 1.6: Tam gic bt kh thi l trng hp c bit ca thuyt t din. Hnh 1.7: S m rng cung tin ca Vit Nam so vi cc nc. Hnh 2.1: So snh mc m ca thng mi cc nc (2006). Hnh 2.2: Dng vn u t vo Trung Quc t 1982-2004. Hnh 3.1: T gi VND/USD ca Vit Nam t 1980-2006. Hnh 3.2: Tng trng tn dng cho nn kinh t ca cc nc 2003-2006.

-8-

DANH MC PH LCPh lc 1.1: M hnh Mundell-Fleming v cc hm v chnh sch ti kho v tin t di cc ch t gi. Ph lc 1.2: Bng 1.2 v 1.3 v s la chn c ch t gi. Ph lc 1.3: nh gi ca ADB v th trng tri phiu ni t Vit Nam 2007. Ph lc 2.1: Ch s CCI ca Trung Quc giai on 1986-2004. Ph lc 2.2: Tm hiu cch phn loi c phiu ca th trng chng khon Trung Quc Ph lc 2.3: Tm hiu th trng c phiu loi B. Ph lc 2.4: Tm hiu lut QFII ca Trung Quc i lc. Ph lc 2.5: Thu ht dng vn ngoi ca Trung Quc v vn dng tin nng. Ph lc 3.1: Kim nh kim sot vn Vit Nam. Ph lc 4.1: Gii thiu m hnh VAR.

-9-

LI M UTrong sut thi gian qua, vn lm pht ang tr thnh ti nng trn c bo ch v gii hc thut. Lm pht nhn c cng chng quan tm bi n tc ng n mm cm ca nhng ngi lao ng ngho, cng nhn, sinh vin, tr thc nhng thnh phn chim i a s trong dn c. Lm pht ang khin cht lng cuc sng ngy cng suy gim, tr thnh mi e do cho mc tiu thin nin k ca Vit Nam. Do vy, kim ch lm pht ang tr thnh mc tiu hng u ca Chnh ph. Th tng Nguyn Tn Dng qua nhng bi pht biu ang gi i thng ip: Ton dn cng tham gia chng lm pht. Nhng gii php, ch trng c xut: ct gim chi tiu cng, thc hin chnh sch tht cht tin tTuy nhin, cha c mt du hiu no cho thy lm pht s chng li. Nm 2007, t l lm pht Vit Nam l 12,36%, nhng ch 5 thng u nm 2008, con s ny ln n 15,96% v nhiu kh nng cn tip tc tng cao. Cc nh u t ang phi tri qua cn b cc ca TTCK Vit Nam. Ch s VN-index gim gn 60% t nh 1171 im vo thng 3/2007. Gn y, ch s VN-index ph mc h tr 400 v tip tc suy gim. Tm l bi quan ang bao trm trn th trng. Cc bin s kinh t v m, khng bao gi l nhng bin s ri rc, m gia chng lun tn ti nhng mi lin kt. Nhn li nhng din bin trong thi gian qua chng ta nhn thy nhng lin kt ny gy ra nhng kh khn nh th no trong vic thc hin mc tiu chng lm pht. NHNN lng tng gia vic mua hay khng mua ngoi t cu chng khon v gi mt t gi c li cho xut khu. Nu mua vo th gy ra lm pht, nhng nu khng mua th chng khon li nh qu bng ri t do, v cc nh xut khu tr nn khn n. Mi gn y, trn li sut cng cho thy s bt nht trong chnh sch chng lm pht. Thng thng, li sut l mt cng c hu dng chng lm pht, nhng lo ngi trc nh hng xu n tng trng kinh t v chng khon suy gim khi li sut huy ng tng cao, NHNN khng ch mc trn cho n. Mc trn ny khin lng tin huy ng ca cc ngn hng st gim, do khng th rt tin trong lu thng chng lm pht. gii quyt vn lm pht, nht thit phi t trong s lin h vi cc bin s kinh t khc nh li sut, tng trng kinh t, tng trng tn dng, ch s VN-index Chnh v l , trong ti ny, chng ti vn dng l thuyt b ba bt kh thi bn lun v vn lm pht, chng khon Vit Nam. T nguyn nhn cho n nhng khuyn ngh s c chng ti a ra khi nghin cu l thuyt b ba kha cnh l lun v thc tin. ti nghin cu c trnh by gm nhng ni dung sau:

- 10 -

Chng 1: L thuyt b ba bt kh thi v cc hm cho Vit Nam. Chng 2: Bi hc t ngi lng ging pha Bc - Trung Quc i Lc. Chng 3: Cc vn thc tin Vit Nam. Chng 4: nh lng cc mi quan h kinh t v m Vit Nam. Chng 5: Con ng no cho chnh sch kinh t Vit Nam.

- 11 CHNG 1: L THUYT B BA BT KH THI V CC HM CHO VIT NAM Gio s Robert Mundell c xem l cha ca l thuyt b ba bt kh thi. Da trn nhng tng ca ng trong tc phm ni ting Chnh sch ti kho v tin t di cc ch t gi (1963), Krugman (1979) v Frankel (1999) pht trin thnh m hnh bt kh thi. Theo l thuyt ny, mt quc gia khng th ng thi t c c ba mc tiu: chnh sch tin t c lp, t gi c nh, v t do ho dng vn. Nghin cu l thuyt ny s em li cho chng ta ci nhn r hn v nhng bin ng kinh t v m ca Vit Nam trong thi gian qua, v cc hm ca l thuyt ny i vi Vit Nam. 1.1.M HNH MUNDELL-FLEMING V CC HM V CHNH SCH TI KHO, CHNH SCH TIN T DI CC CH T GI1 Khi nghin cu tc ng ca chnh sch ti kho v chnh sch tin t i vi vic gia tng sn lng quc gia trong m hnh IS-LM, James Meade(1951) v Jan Tinbergen (1952) c nhng n lc a cc yu t nc ngoi vo m hnh. Tuy nhin, phn ln nhng ng gp ny u ch dng li mc l nhng tranh lun hp dn, cha thc s tr thnh mt l thuyt vng chc. N lc thnh cng nht trong vic a yu t nc ngoi vo h thng l thuyt Keyness hin i c xem l ca m hnh Mundell-Fleming. y l kt qu nghin cu ca Robert Mundell (1962, 1963) v J.M.Fleming (1962) trong thi gian lm vic ti qu tin t quc t IMF. M hnh Mundell-Fleming l s m rng ca nn tng l thuyt IS-LM khi c tnh n tc ng ca cn cn thanh ton. y c xem l im khi u cho l thuyt b ba bt kh thi. M hnh Mundell-Fleming ch ra s hiu qu hay khng hiu qu ca chnh sch tin t v chnh sch ti kho di cc ch t gi khc nhau. 1.1.1.Chnh sch ti kho v chnh sch tin t di ch t gi c nh u tin, m hnh Mundell-Fleming ch ra rng, chnh sch tin t v chnh sch ti kho c th lm thay i cc trng thi ca cn cn thanh ton . Bt u ti im cn bng E trong hnh 1.1, ni m BP=0, nu chng ta thc hin mt chnh sch tin t m rng (mt s dch chuyn sang phi t LM thnh LM) th s c mt im F cn bng mi nm di ng cong BP, v l mt cn cn thanh ton thm ht. Ngc li, bt u t im E, mt s m rng

1

Nhng trnh by chi tit v m hnh IS-LM c a ra trong ph lc 1.

- 12 chnh sch ti kho (ng IS dch chuyn sang phi thnh IS) s hng nn kinh t n mt cn cn thanh ton thng d ti im G. Hnh 1.1: M hnh IS-LM ca Mundell-Fleming vi t gi c nh

Mc d chnh sch tin t v ti kho c th dn n mt cn cn thanh ton thng d hoc thm ht, nhng hm ca m hnh Mundell-Fleming l c th s dng s kt hp ca chnh sch ti kho v tin t tng sn lng m khng to nn mt cn cn thanh ton thm ht hay thng d. iu ny c th hin r trong hnh 1.1. Bt u ti im E, chng ta c th thc hin c hai chnh sch ti kho v tin t m rng (ngha l, IS dch chuyn n IS v LM dch chuyn n LM) nhng vn c c mt cn cn thanh ton cn bng (im H trong hnh 1.1). im H l mt im cn bng bn vng trong di hn. Khi cn cn thanh ton thng d, NHTW s dng ni t mua ngoi t vo. Ngc li, khi cn cn thanh ton thm ht, NHTW s bn ngoi t p ng nhu cu trn th trng. Do , mt cn cn thanh ton thng d hay thm ht s lm tng hoc gim cung tin ca nn kinh t v NHTW s mua vo hoc bn ra ngoi t. Kt qu l, mt cn cn thanh ton thng d hay thm ht s khng c duy tr, nhng iu ny li tc ng n lm pht trong nc. Lun im ny sau c Frankel v Krugman khai thc v xy dng nn l thuyt b ba bt kh thi. Nhm trnh nhng tc ng ca vic mua bn ngoi t n lm pht trong nc nh ni trn, NHTW s dng mt cng c gi l chnh sch v hiu ho. Gi nh, c mt s m rng chnh sch tin t v to ra mt cn cn thanh ton thm ht nh im F trong hnh 1.1. Nu NHTW bn ngoi t nhm p ng cu ngoi t s lm gim cung tin ni a v lm ng LM dch chuyn tr li ng LM, hay mc cn bng s tr li im E. duy tr v tr ti F, NHTW phi tin hnh ci gi l chnh sch v hiu ho, tc l NHTW s mua cc chng khon trn th trng m nhm cung ng ra lu thng mt lng ni t ng bng lng ni t gim i khi NHTW bn ngoi t duy tr cn cn thanh ton thm ht. Ngc li, duy tr mt cn cn thanh ton thng d, chnh sch v hiu ho ca ngn hng c thc hin theo chiu ngc li. Ngha l, NHTW s bn cc chng khon trn th trng m ht lng ni t c dng mua ngoi t trc .

- 13 Tht quan trng hiu cc hm v chnh sch ti kha v tin t di cc mc khc nhau ca lun chuyn dng vn, c ch t gi v chnh sch v hiu ho. Nu chng ta vn tip tc gi nh ch t gi hi oi l c nh v khng c chnh sch v hiu ho, th sau tt yu rng, chnh sch ti kho tr nn hiu qu hn chnh sch tin t. Hy nhn li hnh 1.1 mt ln na. Bt u ti im E, mt s m rng chnh sch tin t s chuyn ng LM sang LM v do t c mt cn cn thanh ton thm ht ti im F. Tuy nhin, khng c s v hiu ho, cung tin s gim v sau LM s dch chuyn sang pha tri tr li LM v im F s quay tr li im E. Ngha l, sn lng sau khi gia tng trong mt thi gian ngn s quay li im cn bng Y*. Do , chnh sch tin t khng hiu qu hon ton lm gia tng sn lng quc gia. Ngc li, gi nh rng, bt u ti im E, chng ta thc hin mt chnh sch ti kha m rng, ng IS dch chuyn sang IS, dn ti mt cn cn thanh ton thng d ti im G. Khng c chnh sch v hiu ho, mt cn cn thanh ton thng d hm rng cung tin s tng nhm p ng cho s gia tng trong sn lng quc gia. Do , ng LM dch chuyn sang pha phi n LM. Ti im cn bng mi, im H, l mt v th di hn. Nh vy, sn lng tng ng k trong trng hp ny v s dch chuyn ca cung tin khi khng c v hiu ho b sung cho s m rng chnh sch ti kho ban u. iu ny a ta n kt lun: di ch t gi c nh, chnh sch ti kho c hiu qu cao hn v chnh sch tin t km hiu qu hn. 1.1.2.Chnh sch ti kho v chnh sch tin t di ch t gi linh hot Cc hm ca chnh sch tin t v chnh sch ti kho di ch t gi linh hot c th c hnh dung trong hnh 1.2. Gi nh chng ta bt u ti E=(r*, Y*) - phn giao nhau ca ng cong IS, LM, BP; v gi nh c mt s m rng chnh sch tin t t LM sang LM. Kt qu, chng ta dch chuyn t E n F, l mt cn cn thanh ton thm ht. Ti im F, c mt cu thng d v ngoi t v cung thng d v ni t trn th trng ngoi hi. Di c ch t gi linh hot, t gi thc s gim, do ng BP dch chuyn sang phi thnh BP v IS dch chuyn sang phi thnh IS, to nn mt im cn bng sn lng mi J cao hn Y*J. Chng ta c c s cn bng bn trong v bn ngoi khi c s giao nhau ca ba ng IS, LM v BP. Do , di ch t gi linh hot, chnh sch tin t t ra kh hiu qu gia tng sn lng. Ngc li, s hiu qu ca chnh sch ti kho di c ch t gi linh hot l khng r rng. Trong hnh 1.2, bt u ti im E, gi nh c mt chnh sch ti kho m rng lm cho ng cong IS dch chuyn n IS ti im G. Tuy nhin, ti im G, chng ta c mt cn cn thanh ton thng d v do c mt s gia tng trong t gi thc. iu ny s lm cho ng BP dch chuyn ln trn thnh BP v IS dch chuyn ngc li thnh IS. Ta c mt im cn

- 14 bng mi K, l s giao nhau ca ng IS, LM v BP. Nh vy, trong iu kin tng i, mt chnh sch ti kho m rng di ch t gi linh hot l t hiu qu hn di ch t gi c nh. Hnh 1.2: M hnh IS-LM ca Mundell-Fleming vi t gi linh hot.

1.2.L THUYT B BA BT KH THI 1.2.1.Thuyt b ba bt kh thi ca GS. Robert Mundell T nhng hm ca m hnh Mundell-Fleming trn ta thy rng: hiu qu ca chnh sch tin t v chnh sch ti kho ph thuc vo c ch t gi hi oi v mc kim sot vn. V d, quc gia no c chuyn dch dng vn t do v t gi c nh, th cc nh qun l tin t khng th theo ui mt chnh sch tin t c lp. Trong mt quc gia c c ch t gi c nh th khng c ri ro t gi, v li sut trong nc bin ng cng vi li sut nc ngoi. T nhng nhn nh trn, cc nh kinh t nh Krugman (1979) v Frankel (1999) m rng m hnh Mundell-Fleming thnh m hnh bt kh thi. Ging nh trong hnh 1.3, Frankel (1999) cho rng, mt quc gia phi t b mt trong 3 mc tiu: chnh sch tin t c lp, s n nh ca chnh sch t gi, v hi nhp th trng ti chnh. Cc ni dung ny c tm tt trong bng 1.1. Hnh 1.3 l s minh ho v nguyn tc hot ng ca b ba bt kh thi. Mi cnh th hin cho cc mc tiu tt nht, ln lt l: chnh sch tin t c lp, s n nh ca t gi, v hi nhp ti chnh hon ton. i nghch vi mi cnh (hay mi mc tiu) l cc cng c chnh sch ti cc nh. Mc tiu hi nhp ti chnh i ngc vi nh kim sot vn; mc tiu n nh t gi i ngc vi nh th ni hon ton; mc tiu chnh sch tin t c lp i ngc vi nh lin minh tin t. Bt k cp mc tiu no cng c th t c bi mt nh nm gia. V d, mc tiu chnh sch tin t c lp v t gi n nh t c bi nh kim sot vn hon ton. Mc tiu chnh sch tin t c lp v hi nhp ti chnh hon ton c th kh thi vi nh th ni hon ton. Cui cng, mc tiu t gi n nh v hi nhp ti chnh t c bi nh lin minh tin t. Hon ton khng kh thi t c ng thi c ba mc tiu.

- 15 -

Bng 1.1- Nguyn l ca b ba bt kh thiDng vn lu ng hon ton Kim sot vn Khng Chnh sch tin t c lp C H thng t gi c nh C Trung Quc trc thng cuc ci cch thng 7/2005 Lin minh tin t T gi th ni C C Khng C C Khng Hng Kng, EU Nht, c V d

1.2.2.Thuyt tam gic m rng ca Yigang v Tangxian Yigang v Tangxian (2001) tip tc pht trin l thuyt b ba bt kh thi ca Mundell v a ln thnh thuyt tam gic m rng. Nn tng ca thuyt ny l nhng quan nim mi v s c lp ca chnh sch tin t v n nh t gi. Theo , b ba bt kh thi ca Mundell kt lun rng mt quc gia khng th c mt chnh sch t gi n nh mt na (half-stability) v chnh sch tin t c lp mt na (half- independence). Ni r hn, tam gic bt kh thi ca Mundell ch mi tp trung n cc c ch t gi nm cc nh (hay gc) tam gic m cha cp n mt c ch t gi trung gian nm u trong tam gic bt kh thi. S tn ti ca c ch t gi trung gian s c bn lun k hn trong phn sau. Yigang v Tangxian m rng m hnh ny v kt lun rng mt quc gia c th c nhng phi hp mc tiu khc nhau v khng phi chp nhn s nh i hon ton nh tam gic ca Mundell. Tng t nh hnh 1.3, ba cnh trong tam gic m rng (hnh 1.4) cng tng ng cho 3 mc tiu chnh sch. Gi nh: cnh M tng trng cho chnh sch tin t c lp; cnh y K, tng trng cho dng vn lu ng hon ho; v cnh phi E, tng trng cho n nh t gi. Ba nh ca gc tam gic tng trng cho 3 cam kt t gi: A1 = c nh, A2 = Th ni hon ton, A3 = lin minh tin t. Gi Ms, Kc v Ev l cc khong cch t im O tu n 3 cnh, tng trng ln lt cho mc ca c lp chnh sch tin t, mc kim sot vn v mc bin ng t gi. Mt tnh cht quan trng ca tam gic u l: tng khong cch ca bt k im no

- 16 bn trong tam gic n ba cnh bng chiu cao ca tam gic. Do ta c Ms + Kc + Ev = Mh. n gin, t chiu cao ca tam gic u Mh = 1, th ta c Ms + Kc + Ev = 1 v 0

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